The present invention relates to a protective means against inertial slip of elevator cab during brake release in an emergency, and more particularly to a protective means cooperated with an escape and protection mechanism of general elevators. When the escape and protection mechanism is actuated by pulling an escape pulling cable to release a braked cab, the protective means works to enable the cab to repeatedly released and braked and thereby move upward or downward at a reduced safety speed to ensure the safety of passengers in the cab. In the event the escape pulling cable is overly pulled, the protective means prevents the escape and protection mechanism from being actuated and the braked cab is not released.
An elevator for high-rise buildings is usually driven to ascend or descend by a driving motor that includes a driving wheel connected to a rotary shaft of the motor. Hoist cables are wound around the driving wheel and driven to lift or lower an elevator cab. There is also an escape and protection mechanism designed for each elevator, such that an elevator cab braked in an emergency could be released manually by pulling an escape pulling cable or mechanically by actuating a stand-by battery. The released elevator cab could therefore move again.
A potential problem existing in the conventional escape and protection mechanism for an elevator cab that employs the principle of counterweight balance is that the brake-released cab tends to ascend or descend at an accelerated speed due to a gravity force and therefore very possibly endangers passengers in the cab.
Another problem with the conventional escape and protection mechanism for an elevator cab is that a panic passenger might very possibly pull the escape pulling cable so hard that some components included in the escape and protection mechanism are damaged or become disordered.
It is therefore tried by the inventor to develop a protective means against inertial slip of elevator cab during brake release in an emergency to overcome the problems existing in the conventional escape and protection mechanism for an elevator.
A primary object of the present invention is to provide a protective means against inertial slip of elevator cab during brake release in an emergency that works to enable a brake-released elevator cab to repeatedly released and braked and thereby move upward or downward at a reduced safety speed to ensure the safety of passengers in the cab.
Another object of the present invention is to provide a protective means against inertial slip of elevator cab during brake release in an emergency that would not work to release a braked elevator cab when the escape pulling cable for actuating the escape and protection mechanism of the elevator is overly pulled.
To achieve the above and other objects, the protective means against inertial slip of elevator cab during brake release in an emergency according to the present invention mainly includes an actuating arm connected at a rear end to the escape pulling cable of an elevator cab, and at a front end to a rear end of a flexible long member. The flexible long member is pivotally connected at a front end to a mechanical control chamber above the elevator cab. The protective means also includes a manual brake release control means having a linking member connected at an upper end to the actuating arm and at a lower end to a cam mounted on the rotary shaft of the driving motor of the elevator. By pulling the escape pulling cable outside the cab with a normal force to decline the actuating arm, the flexible long member is brought downward to press against a manual brake-release shaft connected to the driving motor of the elevator and thereby releases the braked cab. When the cab is released and the driving motor rotates again, the cam mounted on the rotary shaft of the motor rotates at the same time to reciprocate the linking member up and down, causing the flexible member to repeatedly release and press the manual brake-release shaft and thereby intermittently brake and release the cab for the same to move upward or downward at a reduced safety speed.
In the event a panic passenger overly pulls the escape pulling cable, the actuating arm would touch a support near the front end of the actuating arm before the flexible long member is naturally swung downward, resulting in an upward arched flexible long member that does not contact with the manual brake-release shaft to release the braked cab. When the overly pulled escape pulling cable is released and then pulled again with a normal force, the manual brake-release shaft could be depressed by the flexible long member to release the braked cab. In this manner, the whole escape and protection mechanism of the elevator and the protective means of the present invention could function safely.